In orthogonal frequency division multiplexing (OFDM) systems such as long term evolution (LTE) systems, reference signals (RS), which are shared links, are used for channel estimation.
For example, a wireless relay system has been disclosed that uses a wireless relay apparatus to relay a wireless signal from a first wireless station and transmit the wireless signal to a second wireless station. The wireless relay apparatus includes a phase correction amount determining unit that based on channel information related to the transmission path between the first wireless station, the second wireless station, and the wireless relay apparatus, determines the amount of phase correction for the relayed signal; and a phase correcting unit that corrects the phase of the relayed signal, based on the phase correction amount determined by the phase correction amount determining unit (see, for example, Japanese Laid-Open Patent Publication No. 2005-229524).
However, with the conventional technology above, a problem arises in that if the channel resources for reference signals transmitted from multiple points to terminal apparatuses are the same, channel estimation becomes difficult. A further problem arises in that if the reference signals transmitted from multiple points to terminal apparatuses are allocated channel resources so as to prevent the reference signals from being allocated a common (i.e., the same) channel resource, the number of channel resources used for allocation to reference signals increases, whereby channel resource utilization efficiency decreases.